秋季玉米秸秆覆盖对丘陵旱地小麦生理特性及水分利用效率的影响

西南丘陵冬春季节干旱频繁,严重影响小麦播种立苗及产量。2012—2013(干旱)和2013—2014年度(湿润),在四川简阳开展田间试验,比较不同玉米秸秆处理方式对旱地小麦生理性状、水分利用效率及产量的影响。试验共设4个处理,分别是无覆盖(CK)、无覆盖+播后和拔节期灌水(T1)、休闲期覆盖(T2)和休闲期+小麦生育期覆盖(T3)。干旱年份T1、T2和T3的产量分别为4151、3926和3603 kg hm–2;较CK增产42.0%、34.3%和23.2%,提高水分利用效率27.2%、29.6%和18.8%。湿润年份处理间产量差异较小。与CK相比,干旱年份灌水和覆盖提高了播种至开花阶段的干物质积累量,有效抑制了花后旗叶、倒二叶的叶绿素降解;覆盖处理有利于保持播前充足的底墒及生育期间较高的土壤含水量;T2处理主要生育时期的根干重、根冠比、根长密度、根质量密度和根表面积密度增加,下层土壤中的根系增多。籽粒产量与各生育阶段干物质积累量、花后旗叶和倒二叶的SPAD及水分利用效率呈显著或极显著正相关。秋季玉米秸秆就地覆盖具有显著的纳雨保墒作用,可提高小麦立苗质量,延缓叶片衰老,进而增产。

Effects of Autumn Straw Mulching on Physiological Characteristics and Water Use Efficiency in Winter Wheat Grown in Hilly Drought Region

Seasonal drought during winter and spring often occurs in southwest hilly area of China, which severely influences seedling standing and yield in winter wheat. In this study, we conducted a two-year field experiment in Jianyang, Sichuan province in the 2012–2013 (dry) and 2013–2014 (wet) growing seasons to explore the effects of straw mulching on physiological characteristics, water use efficiency (WUE), and grain yield of winter wheat. Four treatments were designed, namely non-mulching (CK), non-mulching plus two irrigations after sowing and at jointing stage (T1), straw mulching before sowing (T2), and straw mulching before sowing and during wheat growth (T3). In the dry year (2012–2013), the yields of T1, T2, and T3 were 4151, 3926, and 3603 kg ha^-1, which were 41.96%, 34.25%, and 23.22% higher than those of CK, respectively, and the WUEs of T1, T2, and T3 increased by 27.23%, 29.59%, and 18.84%, respectively. However, in the wet year (2013–2014), the yield variation among treatments was slight. In the dry year, irrigation or straw mulching showed the effects on enhancing dry matter accumulation from sowing to anthesis and inhibiting SPAD attenuation of flag leaf and penultimate leaf after anthesis and straw mulching increased soil moisture content in pre-sowing and whole growing period. Compared with CK, T2 significantly increased root dry matter, root-to-shoot ratio, root length density, root dry matter density, and root surface area density in some critical growth stages, and highly enhanced root system in deep soil. According to correlation analysis, grain yield was positively correlated with dry matter accumulations in the periods of sowing–tillering, tillering–jointing, jointing–anthesis, and anthesis–maturity, SPAD values of flag and penultimate leaf after anthesis, and WUE. These results indicate that straw mulch before wheat sowing can maintain soil moisture, delay leaf senescence and increase grain yield in winter wheat.